Fuel injected internal combustion engines have in recent years been employed by automotive manufacturers as a more fuel efficient alternative to conventional carbureted engines. Moreover, fuel injected internal combustion engines provide a more accurate means (as compared to carbureted engines) to control a variety of engine operating parameters via an on-board electronic control unit (ECU).
Fuel is typically supplied to the injectors by means of one or more rigid conduits (usually referred to as "fuel rails" in art parlance). The fuel rails are thus adapted to receiving the injectors at spaced-apart locations along the fuel rail so as to be in alignment with respective positions of the intake ports of an internal combustion engine. In such a manner, pressurized fuel from the vehicle's fuel system may be supplied to the individual injectors via the fuel rail.
Fuel pressure regulators are typically provided in the fuel circuit. The conventional fuel pressure regulators are of the "diaphragm" type and serve to maintain the fuel pressure within the fuel rail at an acceptable limit so that the proper fuel flow characteristics to and through the injectors is assured. The fuel regulator is conventionally mounted near (but separately of) the outlet of the fuel rail with suitable conduits establishing fluid communication between it and the discharge end of the fuel rail. The fuel regulator thereby serves to maintain substantially constant upstream fuel pressure within the fuel rails.
As may be appreciated, the conventional technique of separately mounting the regulator requires additional labor during engine production with a concomitant increased production cost. In addition, separate mounting of the regulator causes it to occupy valuable space in the engine compartment. Thus, the separate mounting of the fuel pressure regulator may not be spatially suited to the physical layouts of a number of engine configurations.
One known proposal for incorporating a fuel regulator integrally in a fuel rail is to fashion a recess in the fuel rail and then secure only the upper housing of the regulator (with its associated diaphragm) directly to the fuel rail to achieve an integral fuel rail/regulator assembly. The recess in the fuel rail according to this known proposal thus serves as the bottom housing for the regulator--that is, a separate lower regulator housing structure is unnecessary. While integral mounting of the regulator to the fuel rail is achieved, this prior proposal is disadvantageous in that the regulator itself cannot be calibrated and/or leak tested independently of the fuel rail (i.e., since it does not physically have a lower housing). Instead, calibration and/or leak testing can only be achieved after the regulator is integrally mounted to the fuel rail--a cumbersome, if not costly, procedure.
Therefore, what has been needed in this art, at least from an economy of labor and space point of view, is a fuel rail assembly which provides the means by which a fuel pressure regulator may be integrally operatively associated therewith, while at the same time, allow calibration and/or leak testing of the regulator independently of the fuel rail prior to assembly. It is towards achieving such advantages that the present invention is specifically directed.
According to the present invention, a fuel rail assembly is provided which includes at least one rigid tubular fuel rail for supplying fuel to a number of fuel injectors dependently positioned in fluid communication with the rail. The tubular fuel rail includes a mounting section which defines a recess for accepting a lower portion of the fuel regulator housing, and which establishes with this lower fuel regulator housing an annular chamber in fluid communication with the fuel passageway of the tubular fuel rail. The lower regulator housing moreover defines at least one aperture which fluid-connects the defined annular chamber with a fuel regulating chamber physically located within the fuel pressure regulator. Hence, fuel may flow into the regulator from the fuel rail via the defined annular chamber, whereby the pressure of the fuel within the fuel rail may be regulated.
The mounting section of the fuel rail assembly according to this invention is, in a preferred embodiment, generally rectangular in cross-sectional geometry so as to provide substantially planar upper and lower wall regions. The upper and lower wall regions respectively define upper and lower separated (but preferably coaxially registered) apertures and are collectively adapted to receive a tail section of a fuel regulator mounting cup.
The regulator mounting cup includes an upper cup section which is rigidly connected to, and supported by, the upper wall of the mounting section and defines a number of arcuately shaped openings therethrough. These defined openings are in registry with a portion of the upper aperture and thus establish, collectively with the upper aperture, a fluid flow path from the tubular fuel rail to the cup section of the regulator mounting cup. The fuel then enters the fuel regulator (through openings in the regulator's lower housing) and is discharged from its outlet into the regulator mounting cup's tail section. An outlet nipple in fluid communication with this tail section then directs the fuel to the return side of the vehicle's fuel system.
Other aspects and advantages of this invention will become more clear after careful consideration is given to the detailed description of the preferred exemplary embodiments thereof which follows.